Heart Rate Variability as a Predictor of Rebound Pain Following Total Knee Arthroplasty

This study aims to investigate whether heart rate variability (HRV), a marker of autonomic nervous system activity, can predict the occurrence of rebound pain after total knee arthroplasty (TKA). Rebound pain is defined as a sudden and intense pain episode (NRS ≥7) that typically arises after the resolution of peripheral nerve blocks used for postoperative analgesia.

Patients undergoing elective unilateral TKA under spinal anesthesia with peripheral nerve blocks will be included. HRV will be measured both before and after surgery using a chest-worn heart rate monitor. Pain levels, analgesic consumption, sleep quality, and patient satisfaction will also be recorded. The primary goal is to determine whether perioperative HRV values can serve as a predictive biomarker for rebound pain.

Secondary outcomes include the relationship between HRV and pain intensity, opioid use, sleep quality, and length of hospital stay. The findings may contribute to developing individualized pain management strategies for TKA patients.

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Key information

Conditions

Rebound Pain Heart Rate Variability Neurologic Manifestations Pain Pain, Postoperative Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Complications Postoperative Pain, Chronic Signs and Symptoms Total Knee Arthroplasty

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Konya City Hospital

Konya, 42090, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Age between 18 and 70 years
American Society of Anesthesiologists (ASA) physical status I-III
Scheduled for elective, unilateral total knee arthroplasty under spinal anesthesia
Planned use of multimodal analgesia including peripheral nerve blocks
Ability to provide written informed consent
Ability to understand and complete pain diaries and questionnaires

Exclusion criteria

Known allergy to local anesthetics
Contraindications to regional anesthesia
Contraindications to spinal anesthesia
ASA physical status IV or higher
Pregnancy or breastfeeding
Neurological or psychiatric disorders impairing ability to participate or report outcomes
Use of anticoagulant therapy or presence of coagulation disorders
Infection at the proposed injection site
Emergency (non-elective) surgical procedures

Treatment and study plan

Primary outcomes

Preoperative LF/HF Ratio as a Predictor of Rebound Pain

Time frame: Preoperative (before spinal anesthesia) to 48 hours postoperative

To determine whether the preoperative low frequency to high frequency (LF/HF) ratio of heart rate variability is associated with the development of rebound pain after peripheral nerve block resolution. Patients will be classified based on the presence or absence of rebound pain (defined as a shift from NRS ≤3 to ≥7), and mean LF/HF ratios will be compared. Predictive capacity will be evaluated using logistic regression and ROC analysis.

Secondary outcomes

Association Between HRV Parameters and Pain Intensity

Time frame: 0-48 hours postoperative

Correlation between perioperative HRV values (SDNN, RMSSD, LF/HF) and postoperative pain scores (measured by NRS at 8h, 12h, 16h, 24h, and 48h).

Sponsors and collaborators

Lead sponsor

Konya City Hospital

Other

Registry information

Official study title

The Role of Perioperative Heart Rate Variability in Predicting Rebound Pain After Total Knee Arthroplasty: A Prospective Observational Study

Important dates

Study start: 2025
Primary completion: 2025
Study completion: 2025
First posted: May 18, 2025
Registry last updated: Jan 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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Completed